板凳没坐热

板凳没坐热

Literally means:

one is seated on the stool for such a short time that the stool has not got warm by his body heat yet.

Actually means:

It figuratively means one stays in a place or a position for short time before he leaves. It also means something new happens within short time. It carries a humorous tone.

在板凳上坐的时间不长，体温还没有把板凳捂热。

形容在某一地方或者某一职位只停留极短的时间就离开了，也指在极短的时间内就有新情况发生。有诙谐的意味。